Bertha’s Demise

RGB Satellite imagery with Tropical Storm Bertha circled in red, and the broad coastal low indicated by the counter-clockwise blue arrows. Only thin cirrus near Bermuda at the time, but showers and thunderstorms with the broad low are expected to expand and push towards Bermuda overnight.

Hurricane Bertha weakened yesterday afternoon from hurricane status as the deep convection near the center collapsed and left the center an exposed low cloud swirl once again. However, this morning and through the day, intermittent bursts of deep convection have covered the center so Bertha has seen only a gradual weakening and stands as a tropical storm with 50mph maximum 1-minute sustained winds.

Bertha has now begun to turn more northeastward and is expected to accelerate in that direction, passing south of Nova Scotia Wednesday while becoming post-tropical/extra-tropical and south of Newfoundland Wednesday night/Thursday morning. Past Thursday morning, Bertha will continue eastward into the central north Atlantic and continue to weaken.

Bertha is caught in the southwesterly flow around the western side of the deep-layered Bermuda Azores high. This flow is also ahead of a stationary front lined along the US East coast. A broad area of low pressure exists along the tail end of this stationary front and is interacting with Bertha. As Bertha becomes post-tropical, it will drag this area of low pressure to the north of Bermuda, and the associated front is dragged across Bermuda. This will introduce showers with gusty winds and possible thunder starting as early as Wednesday morning and peaking in activity overnight into Thursday morning. Gusts could reach gale force in and around some of the heavier showers. Rainfall totals are expected to be near an inch – this is much needed rain as it has been fairly dry lately with the Bermuda-Azores high firmly in control. The front then lingers near Bermuda dissipating, but convergence associated with its remains keeps a chance of isolated showers in the forecast into Saturday.

Meanwhile in the Central Pacific, the Central Pacific Hurricane Center has issued a tropical storm watch for the big island of Hawaii. This is because Hurricane Iselle is approaching from the east as a gradually weakening category two hurricane. The current forecast brings a Iselle near the Big Island as a strong Tropical Storm.